The technology relates to an automatic transmission that utilizes a shift-by-wire system in which shift ranges are automatically switched from one to another with use of an actuator. In particular, the technology relates to a shift-by-wire control apparatus that forcibly switches any shift range to a parking range in response to a state of a vehicle.
A vehicle automatic transmission may utilize a shift-by-wire system in which shift ranges, including a drive (D) range, a reverse (R) range, a neutral (N) range, and a parking (P) range, are switched from one to another with use of an actuator such as a solenoid. For such an automatic transmission, for purpose of improving safety, an auto parking control technique is known in which any shift range is forcibly switched to the parking range, on a condition that the shift range other than the parking range is set when a driver has stopped a vehicle and leaves the vehicle.
For example, Japanese Unexamined Patent Application Publication (JP-A) No. 2013-199963 discloses a technique in which any shift range is forcibly switched to the parking range by determining that a vehicle is in preparation for stopping, on conditions that a door at a driver's seat is detected as being open and a seat belt of a driver is detected as being not fastened by the driver. For another example, JP-A No. 2003-156140 discloses a technique in which any shift range of a vehicle is forcibly shifted to the parking range, on a condition that the shift range other than the parking range is set upon detection of driver's action of leaving a vehicle. Furthermore, for purposes of preventing erroneous operation and improving safety, JP-A No. 2007-170546 discloses a technique in which any shift range is switched to the parking range, on a condition that a vehicle speed is less than a predetermined speed, a seat belt is not fastened by a driver, and a load applied onto a driver's seat is equal to or less than a predetermined value.